/*  XMMS - Cross-platform multimedia player
 *  Copyright (C) 1998-2000  Peter Alm, Mikael Alm, Olle Hallnas, Thomas Nilsson and 4Front Technologies
 *
 *  This program is free software; you can redistribute it and/or modify
 *  it under the terms of the GNU General Public License as published by
 *  the Free Software Foundation; either version 2 of the License, or
 *  (at your option) any later version.
 *
 *  This program is distributed in the hope that it will be useful,
 *  but WITHOUT ANY WARRANTY; without even the implied warranty of
 *  MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE.  See the
 *  GNU General Public License for more details.
 *
 *  You should have received a copy of the GNU General Public License
 *  along with this program; if not, write to the Free Software
 *  Foundation, Inc., 59 Temple Place - Suite 330, Boston, MA 02111-1307, USA.
 */
#include "xmms.h"

void init_spline(gfloat * x, gfloat * y, gint n, gfloat * y2)
{
	gint i, k;
	gfloat p, qn, sig, un, *u;

	u = (gfloat *) g_malloc(n * sizeof (gfloat));

	y2[0] = u[0] = 0.0;

	for (i = 1; i < n - 1; i++)
	{
		sig = ((gfloat) x[i] - x[i - 1]) / ((gfloat) x[i + 1] - x[i - 1]);
		p = sig * y2[i - 1] + 2.0;
		y2[i] = (sig - 1.0) / p;
		u[i] = (((gfloat) y[i + 1] - y[i]) / (x[i + 1] - x[i])) - (((gfloat) y[i] - y[i - 1]) / (x[i] - x[i - 1]));
		u[i] = (6.0 * u[i] / (x[i + 1] - x[i - 1]) - sig * u[i - 1]) / p;
	}
	qn = un = 0.0;

	y2[n - 1] = (un - qn * u[n - 2]) / (qn * y2[n - 2] + 1.0);
	for (k = n - 2; k >= 0; k--)
		y2[k] = y2[k] * y2[k + 1] + u[k];
	g_free(u);
}

float eval_spline(gfloat xa[], gfloat ya[], gfloat y2a[], gint n, gfloat x)
{
	gint klo, khi, k;
	gfloat h, b, a;

	klo = 0;
	khi = n - 1;
	while (khi - klo > 1)
	{
		k = (khi + klo) >> 1;
		if (xa[k] > x)
			khi = k;
		else
			klo = k;
	}
	h = xa[khi] - xa[klo];
	a = (xa[khi] - x) / h;
	b = (x - xa[klo]) / h;
	return (a * ya[klo] + b * ya[khi] + ((a * a * a - a) * y2a[klo] + (b * b * b - b) * y2a[khi]) * (h * h) / 6.0);
}

void eqgraph_draw(Widget * w)
{
	EqGraph *eg = (EqGraph *) w;
	GdkPixmap *obj;
	GdkColor col;
	guint32 cols[19];
	gint i, y, ymin, ymax, py = 0;
	gfloat x[] = {0, 11, 23, 35, 47, 59, 71, 83, 97, 109}, yf[10];

	/*
	 * This avoids the init_spline() function to be inlined.
	 * Inlining the function caused troubles when compiling with
	 * `-O' (at least on FreeBSD).
	 */
	void (*__init_spline)(gfloat *, gfloat *, gint, gfloat *) =
	    init_spline;

	obj = eg->eg_widget.parent;
	skin_draw_pixmap(obj, eg->eg_widget.gc, SKIN_EQMAIN,
			 0, 294, eg->eg_widget.x, eg->eg_widget.y,
			 eg->eg_widget.width, eg->eg_widget.height);
	skin_draw_pixmap(obj, eg->eg_widget.gc, SKIN_EQMAIN,
			 0, 314, eg->eg_widget.x,
			 eg->eg_widget.y + 9 + ((cfg.equalizer_preamp * 9) / 20),
			 eg->eg_widget.width, 1);

	skin_get_eq_spline_colors(&cols);

	__init_spline(x, cfg.equalizer_bands, 10, yf);
	for (i = 0; i < 109; i++)
	{
		y = 9 - (gint) ((eval_spline(x, cfg.equalizer_bands, yf, 10, i) * 9.0) / 20.0);
		if (y < 0)
			y = 0;
		if (y > 18)
			y = 18;
		if (!i)
			py = y;
		if (y < py)
		{
			ymin = y;
			ymax = py;
		}
		else
		{
			ymin = py;
			ymax = y;
		}
		py = y;
		for (y = ymin; y <= ymax; y++)
		{
			col.pixel = cols[y];
			gdk_gc_set_foreground(eg->eg_widget.gc, &col);
			gdk_draw_point(obj, eg->eg_widget.gc, eg->eg_widget.x + i + 2, eg->eg_widget.y + y);
		}
	}
}

EqGraph *create_eqgraph(GList ** wlist, GdkPixmap * parent, GdkGC * gc, gint x, gint y)
{
	EqGraph *eg;

	eg = (EqGraph *) g_malloc0(sizeof (EqGraph));
	eg->eg_widget.parent = parent;
	eg->eg_widget.gc = gc;
	eg->eg_widget.x = x;
	eg->eg_widget.y = y;
	eg->eg_widget.width = 113;
	eg->eg_widget.height = 19;
	eg->eg_widget.visible = TRUE;
	eg->eg_widget.draw = eqgraph_draw;
	add_widget(wlist, eg);
	return eg;
}
